A shock absorber is mounted, for example, to a vehicle such as an automobile and reduces vibration of a vehicle body by generating a damping force. In such a shock absorber, it is proposed to employ a choke passage that generates a damping force when a piston speed is low.
JP2012-167785A discloses a shock absorber that includes a cylinder, a rod movably inserted inside the cylinder, and a piston that is brought into sliding contact with an inner periphery of the cylinder to partition the inside of the cylinder into two action chambers. A case member with an approximately cylindrical shape is screwed with a distal end of the rod. The piston is formed in an annular shape and held on the outer periphery of the case member to be coupled to the rod.
In this shock absorber, a choke member is inserted into the case member. A choke groove with a spiral pattern is disposed on the outer periphery of the choke member. The inner peripheral surface of the case member and the choke groove form a choke passage with a spiral pattern that communicates with the two action chambers inside the cylinder.